Motor Vehicle with Simulator of Performance of a Mechanical Gearbox

ABSTRACT

A vehicle having a motor with a transmission, provided with a fixed gear ratio, to a propelling unit includes a virtual gearbox including a microprocessor, operatively interfaced with the motor and programmed to manage and check the generation of motor driving torque, limiting, at the motor output, a maximum angular velocity and a maximum torque which are variable with a predetermined law.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/678,211, filed Feb. 23, 2022, which is a continuation of U.S.application Ser. No. 16/327,442, filed Feb. 22, 2019, now U.S. Pat. No.11,299,048, which is the National Phase of International ApplicationPCT/IT2017/000207, filed Sep. 26, 2017, which designated the U.S. andthat International Application was published under PCT Article 21(2) inEnglish, and claims priority to Italian Application No. 102016000096737,filed Sep. 27, 2016, the contents of which are hereby incorporated byreference in their entireties.

TECHNICAL FIELD

This invention relates to a motor vehicle having a transmission withfixed gear ratio to a propelling unit, equipped with a simulator of theperformance of a mechanical gearbox.

BACKGROUND ART

As is known, the performance of a vehicle propulsion motor is defined bymeans of mechanical characteristics consisting of the torque “C” and themaximum angular velocity “n” of the motor, whilst the performance of avehicle equipped with the motor is characterised by two mechanicalparameters, consisting of the tractive force “F” at the driving wheels,that the vehicle must apply in order to move a working load, and thespeed “V” at which the movement occurs.

In vehicles, operation of the mechanical gearbox allows the achievementof high vehicle tractive forces (and, therefore, high levels ofacceleration) in low gears, correlated with low speeds, and low tractiveforces but high speeds with high gears.

The performance of certain types of vehicle having a transmission withfixed gear ratio (final drive ratio)—as is the case, for example, incertain vehicles for recreational activities, such as go-karts whichtake their motive power from a direct drive electric motor—generallyspeaking for some categories of users is not as entertaining andenthralling as that which could otherwise be obtained using an internalcombustion engine. The latter, in contrast, comprises a gearbox withvariable gear ratios, interposed between the engine and the axle, andwhich transmits to the wheels the engine power factors (torque andangular velocity n), modified depending on the desired, or necessary,temporary propulsion conditions of the vehicle at the various gearsprovided by the gearbox.

To satisfy such a type of demand from users, there are already prior artsimulators comprising an electronically actuated gearbox, managed byelectronic operating and checking means, that the user controls usinggear selectors which can be operated from the steering wheel of thevehicle driving position.

Disadvantageously, these simulators have many moving parts which, on onehand have a negative effect on vehicle performance reliability, makingfrequent maintenance necessary and thereby rendering such simulators notvery suitable for rental vehicles; and, on the other hand, make thevehicle heavy, penalising its racing performance; and increase vehiclecosts.

Another disadvantage of these systems is the fact that they offer fixedreduction ratios (i1;i2;i3; . . . in) that are often not suitable forthe circuit or for the driving style of the driver and that require moreor less complex and expensive operations in order to change them.

On the other hand, the use of a mechanical gearbox may also bedisadvantageous at a commercial level, considering the increase in coststhat may apply to the vehicle due to the physical presence of thegearbox and the clutch.

DISCLOSURE OF THE INVENTION

The aim of this invention is to overcome the disadvantages of the priorart, by means of electronic simulation of a mechanical gearbox withvariable gear ratios, which can be implemented practically without useof additional parts that have weight and of significantly appreciablemovement for the configuration of the vehicle.

In accordance with the invention, that result is achieved by a vehicledefined as in any of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of the invention are more apparent in the detaileddescription which follows, with reference to the accompanying drawingswhich illustrate an example, non-limiting embodiment of the invention,in which:

FIG. 1 is a schematic functional block diagram of a vehicle according tothis invention.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

With reference to FIG. 1 of the accompanying drawings, the numeral (1)denotes in its entirety a vehicle having a motor (10) with atransmission (11), with fixed gear ratio (ip), to a propelling unit (12)shown as the driving wheels of the vehicle (1).

The vehicle (1) is preferably—by way of example and without limiting theinvention—a go-kart equipped with an electric motor (10).

The motor (10) and the transmission (11) can be dynamically connected bya coupling (17) that makes the motor (10) independent of the wheels (12)and that, once the motor (10) has been started with no load, allowsgradual application of the external load.

The vehicle (1) comprises a virtual gearbox (13), that is to say, asimulator of the performance of a mechanical gearbox whichelectronically simulates the latter by means of suitable real-time checkof the parameters for generating and supplying driving torque for themotor (10).

More particularly, said virtual gearbox (13) comprises microprocessormeans (14), located on a suitable printed circuit board, which areoperatively interfaced with the motor (10) and programmed to manage andcheck the generation of the maximum driving torque (Co) parameters, withconstant power, preferably maximum, and with angular velocity (n at themotor (10) output, that is to say, at the transmission (11) input, whichare variable, with a suitably predetermined law.

The variable velocity (n) is correlated with a corresponding drivingtorque of the motor (10) according to variable gear ratios (i1;i2;i3; .. . in), preferably with separate values relating to the different gearsthat a hypothetical discontinuous speed variation mechanical gearboxwould have, if the latter were actually and physically present in thevehicle (1).

Selecting means (15) for selecting the velocity (n) at the transmission(11) input are provided associated with a steering wheel (20) of thevehicle (1). Said selecting means can be activated with a manualcommand, deliberately, issued by the vehicle driver, from the steeringwheel (20), and transmitted as input to the microprocessor means (14)for starting

-   -   for each characteristic gear of the virtual gearbox (13)—and in        real time all of the processing operations that allow a        corresponding suitable electric motor (10) management in terms        of torque (C) and corresponding angular velocity (n) with        vehicle (1) constant power, preferably maximum.

Obviously, the microprocessor means (14) can manage the supply ofdriving power even according to different functions, which are in anycase correlated with the simulation of an automatic gearbox that is realand physically present on the vehicle (1).

In fact, they can allow simulation, via software, even of a variation ofthe velocity (n) according to multiple gear ratios (i1;i2;i3 . . . in),whose values are programmable as desired by the user, for example,according to a mathematical progression, different on each occasion, forexample selected relative to distinctive features of the various trackson which the go-kart may race.

Moreover, the microprocessor means (14) may manage the operatingparameters of the electric motor (10) in such a way as to also generate,if necessary, a counter-driving torque useful for vehicle (1) braking.

That function can be exploited, for example, to advantageously simulatedownshifting, that is to say, “engine braking” due, for example, tointrinsic friction of an internal combustion engine. Therefore, allconditions able to give the vehicle driver sensations of inertia, ofmass, like those that would be felt when driving a vehicle powered by aninternal combustion engine.

Moreover, said counter-driving force may be modulated, even withvariable intensity using a different law of variation, depending on thevirtual gear, in the progression of gears of the gearbox, or in the idlestate in which the vehicle (1) is stationary with the motor (10)running.

The microprocessor means (14) can also allow generation of the drivingtorque (Co) of the motor (10) simulating the law of progression duringacceleration (picking up again, or from a standing start) of a realvehicle operating with inertias and frictions whose numerical values areprocessed by the microprocessor means (14).

The microprocessor means (14) can manage operating parameters of theelectric motor (10) even simulating engagement and disengagement of amechanical clutch.

Sound reproducing means (16) can also be provided, for reproducingsounds, corresponding to the sound spectrum of a real internalcombustion engine (10), sounds that are harmonised, depending on themotor (10) speed, where the expression virtual speed means the speedthat an engine system would have with a gearbox having the same gearratio selected as in the virtual gearbox.

In the above description reference was made to a vehicle able to movewith a torque (C) and velocity (n) which are variable according to agear ratio (i) that is stepped, that is to say, having a series ofseparate predetermined ratios. However, it is clear that the drivingtorque supply parameters of the motor (10) may also be implemented insuch a way as to simulate a continuously variable transmission if thatlaw of simulation is of interest.

To better explain several distinctive features of the invention, thefollowing non-limiting comparison may be used by way of example.Consider a vehicle with a hypothetical mechanical gearbox havingseparate ratios and reduction ratios of i1=2, i2=1.5 and i3=1, with aconstant torque curve equal to 50 Nm and n=5,000 rpm, maximum values,which respectively allow the achievement of maximum speeds for each gearof 25 km/h, 37.5 km/h and 50 km/h, with respective torques at the wheelsof 100 Nm, 75 Nm and 50 Nm. Then take a vehicle with the inventioninstalled and install a motor (10) able to supply a constant torque of100 Nm from 0 to 5,000 rpm, with a fixed reduction ratio if=1. Whenvirtual gear No. 1 is engaged in the vehicle, the electric motor is setin real time to supply a maximum of 100 Nm of torque from 0 to 2,500rpm, allowing the vehicle to reach the maximum speed of 25 km/h with atorque at the wheels of 100 Nm, precisely as in vehicle 1 in gear No. 1.Then, when virtual gear No. 2 is engaged, the electric motor (10) ischoked so that it supplies a maximum of 75 Nm of torque at the wheelswith a maximum speed of 37.5 km/h, just like in gear No. 2 of thevehicle equipped with the mechanical gearbox, and so on.

It is possible to calculate the virtual revolutions per minute (rpm) ofthe electric motor (10) in order to make them equivalent to the motor(10) that has a mechanical gearbox. In that way, with virtual gear No. 1engaged, when the vehicle reaches the speed of 25 km/h, the virtualrevolutions per minute (rpm) are 5,000. This makes it possible toreproduce a simulated sound that emulates the tone of a motor (10) witha gearbox, and to reproduce on a display the virtual rpm of the motor,in a condition such that, for example, first gear is engaged and the revcounter is at the full-scale position, when the rpm are 2,500 (but thevirtual rpm are 5,000).

The invention achieves the proposed aims, also providing the additionaladvantages of high levels of operating effectiveness and stability, aswell as being inexpensive to make, maintain and use.

In conclusion, the invention operates by performing fully electronicadjustment and management of the drive unit driving power generating andsupplying curves, operations that are carried out in real time as avirtual simulation of the dynamics of a vehicle equipped with amechanical gearbox having multiple gears. All of that is done despitethe fact that the vehicle in question is actually fitted with a physicaltransmission having a single, fixed ratio.

The invention described above is susceptible of evident industrialapplication. It may also be modified and adapted in several ways withoutthereby departing from the scope of the following claims.

Moreover, all details of the invention may be substituted by technicallyequivalent elements.

1. A method comprising: receiving a speed of a vehicle from a speedgauge of the vehicle; receiving an acceleration level from anacceleration pedal of the vehicle; setting limits of a maximum angularvelocity and a maximum torque of an electrical motor according to apredetermined rule, wherein the predetermined rule is set according tothe speed of the vehicle; and providing, by the electric motor, anangular velocity and a torque to a transmission with a fixed gear ratioaccording to the acceleration level, the maximum angular velocity, themaximum torque, and the speed of the vehicle.
 2. The method of claim 1,wherein the limits of the maximum angular velocity and the maximumtorque simulate a plurality of gear ratios of a gearbox.
 3. The methodof claim 1, wherein the angular velocity and the torque generate acounter-driving power according to the acceleration level being anegative acceleration.
 4. The method of claim 3, wherein thecounter-driving power has a variable intensity that varies according tothe speed and acceleration level.
 5. The method of claim 3, wherein thecounter-driving power: is used for vehicle braking; simulatesdownshifting; or simulates engine braking caused by intrinsic frictionof an internal combustion engine.
 6. The method of claim 1, comprising:receiving a clutch slip level; and simulating, using the angularvelocity and the torque, an engagement and a disengagement of amechanical clutch according to the clutch slip level.
 7. The method ofclaim 1, comprising reproducing a sound according to the angularvelocity and the torque, wherein the sound corresponds to a realinternal combustion engine in a same condition.
 8. The method of claim1, wherein the torque and the angular velocity are variable according toa continuously variable transmission.
 9. The method of claim 1,comprising receiving a gear selection, wherein the torque and theangular velocity are determined according to the gear selection.
 10. Themethod of claim 9, wherein the selecting is activated automatically. 11.A vehicle comprising: a speed gauge; an acceleration pedal; anelectrical motor; a transmission comprising a fixed gear ratio; and anda microprocessor configured to: receive a speed of the vehicle from thespeed gauge; receive an acceleration level from the acceleration pedal;receive a predetermined rule; set limits of a maximum angular velocityand a maximum torque of the electrical motor according to thepredetermined rule, wherein the predetermined rule is set according tothe speed of the vehicle; and provide, by the electric motor, an angularvelocity and a torque to the transmission according to the accelerationlevel, the maximum angular velocity, the maximum torque, and the speed.12. The vehicle of claim 11, wherein the limits of the maximum angularvelocity and the maximum torque simulate a plurality of gear ratios of agearbox.
 13. The vehicle of claim 11, wherein the angular velocity andthe torque generate a counter-driving power according to theacceleration level being a negative acceleration.
 14. The vehicle ofclaim 13, wherein the counter-driving power has a variable intensitythat varies according to the speed and acceleration level.
 15. Thevehicle of claim 13, wherein the counter-driving power: is used forvehicle braking; simulates downshifting; or simulates engine brakingcaused by intrinsic friction of an internal combustion engine.
 16. Thevehicle of claim 11, wherein the microprocessor is configured to:receive a clutch slip level; and simulate, using the angular velocityand the torque, an engagement and a disengagement of a mechanical clutchaccording to the clutch slip level.
 17. The vehicle of claim 11, whereinthe microprocessor is configured to: reproduce a sound according to theangular velocity and the torque, wherein the sound corresponds to a realinternal combustion engine in a same condition.
 18. The vehicle of claim11, wherein the torque and the angular velocity are variable accordingto a continuously variable transmission.
 19. The vehicle of claim 11,wherein the microprocessor is configured to: receive a gear selection,wherein the torque and the angular velocity are determined according tothe gear selection.
 20. The vehicle of claim 19, wherein the selectingis activated automatically.